Exotic mechanical properties enabled by countersnapping instabilities

• 成果类型: Article
• 署名作者: Ducarme, Paul; Weber, Bart; van Hecke, Martin; Overvelde, Johannes T. B.
• 署名单位: AMOLF; AMOLF; University of Amsterdam; Leiden University; Leiden University - Excl LUMC; Eindhoven University of Technology
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-11266
• DOI: 10.1073/pnas.2423301122
• 发表日期: 2025-04-22
• 关键词: snap-through; metamaterials; optimization; patterns; BEHAVIOR

摘要

Mechanical snapping instabilities are leveraged by natural systems, metamaterials, and devices for rapid sensing, actuation, and shape changes, as well as to absorb impact. In all current forms of snapping, shapes deform in the same direction as the exerted forces, even though there is no physical law that dictates this. Here, we realize countersnapping mechanical structures that respond in the opposite way. In contrast to regular snapping, countersnapping manifests itself in a sudden shortening transition under increasing tension or a sudden increase in tensile force under increasing extension. We design these structures by combining basic flexible building blocks that leverage geometric nonlinearities. We demonstrate experimentally that countersnapping can be employed to obtain new exotic properties, such as unidirectional stick-slip motion, switchable stiffness that does not otherwise affect the state of the system, and passive resonance avoidance. Moreover, we demonstrate that combining multiple countersnapping elements allows sequential stiffness switching for elements coupled in parallel, or instantaneous collective switching for elements in series. By expanding the repertoire of realizable elastic instabilities, our work opens routes to principles for mechanical sensing, computation, and actuation.